Search

Orbital tuning is a technology for adjusting the time scale of a geological or climate record to achieve maximum synchronization with the cycles of orbital motion (insolation) presented in astronomical climate theory. The procedure for coordinating climatic events with orbital insolation cycles seems natural due to the fact that solar radiation is the main source of energy for hydrometeorological, biochemical, soil biological and other processes that determine the state and dynamics of the natural system of the Earth. The climate is a generalized characteristic of the state of the natural system. A paradox was found in the change in insolation and temperature in the Holocene. Based on the analysis of the causes of the Holocene paradox, it is shown that the technologies of orbital adjustment relative to the calculations of insolation performed in the astronomical climate theory are premature. The main problem of orbital alignment is to accept the direct dependence of temperature on insolation and not take into account the influence of insolation-related heat transfer mechanisms on the Earthʼs temperature regime. It is shown that, with correct calculated insolation data, the climatic–stratigraphic scale of the astronomical theory of climate is not complete or objective without taking into account the temperature changes caused by the mechanisms of heat transfer. [ABSTRACT FROM AUTHOR]

Abrupt climate changes constitute a relatively new field of research, which addresses variations occurring in a relatively short time interval of tens to a hundred years. Such time scales do not correspond to the tens or hundreds of thousands of years that the astronomical theory of climate addresses. The latter theory involves parameters that are external to the climate system and whose multi-periodic variations are reliably known and almost constant for a large extent of Earth history. Abrupt changes, conversely, appear to involve fast processes that are internal to the climate system; these processes varied considerably during the past 2.6 Myr, and yielded more irregular fluctuations. In this paper, we re-examine the main climate variations determined from the U1308 North Atlantic marine record, which yields a detailed calving history of the Northern Hemisphere ice sheets over the past 3.2 Myr. The magnitude and periodicity of the ice-rafted debris (IRD) events observed in the U1308 record allow one to determine the timing of several abrupt climate changes, the larger ones corresponding to the massive iceberg discharges labeled Heinrich events (HEs). In parallel, abrupt warmings, called Dansgaard-Oeschger (DO) events, have been identified in the Greenland records of the last glaciation cycle. Combining the HE and DO observations, we study a complex mechanism that may lead to the observed millennial-scale variability corresponding to the abrupt climate changes of last 0.9 Myr. This mechanism relies on amended Bond cycles, which group DO events and the associated Greenland stadials into a trend of increased cooling, with IRD events embedded into every stadial, the latest of these being an HE. These Bond cycles may have occurred during the last 0.9 Ma when Northern Hemisphere ice sheets reached their maximum extent and volume, thus becoming a major player in this time interval's climate dynamics. Since the waxing and waning of ice sheets during the Quaternary period are orbitally paced, we conclude that the abrupt climate changes observed during the Mid and Upper Pleistocene are therewith indirectly linked to the astronomical theory of climate. [ABSTRACT FROM AUTHOR]